Thermal treatment of synthetic textiles



Nov. 8, 1966 H. CROUZET 3,

THERMAL TREATMENT OF SYNTHETIC TEXTILES Filed March 4, 1964 .rll LL,

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INVENTOR. HENRI CROUZET ATTORNEY United 1 States Patent i Filed Mar. 4,1964, Ser. No. 349,370 4 Claims. (Cl. 34-77) Synthetic yarns of allkinds are oiled at the time of spinning, and the oil, called size, formsa covering around each filament of which the yarn is composed whichregularises and facilitates the sliding of the yarn in the course of thestretching and in the course of the subsequent textile transformations.

In some further treatments, for example for crimping and/ or increasingthe bulk, the yarn is subjected to heating at high temperature, whichmay reach, for example, 230 C. or 240 C. in the case of polyamides 66.

This temperature is above the vaporization temperature of the sizingoils, which become converted into fumes and recondense in the form ofoil, or become carbonized with the formation of solid deposits in theheating element.

The effect of fumes and deposits becomes more troublesome with theincrease in the speed of travel of the yarn, which is being constantlyincreased for the purpose of increasing the output of machines.

In order to obviate the liberation of fumes into the atmosphere, use isgenerally made of smoke extractors. In such cases, condensation in theheating elements, which are generally vertical, is avoided by usingeither detachable condensers, which are thus easy to clean, or ofheating devices having a sufiicient cross-section to permit the naturaloccurrence of a chimney effect, which produces a movement of air wherebythe greater part of the heavy fumes is entrained and their condensationin the heating elements is also partially avoided.

The use of heating devices of large cross-section increases theconsumption of heat and reduces the transmission of heat by radiation,which is maximum when the heating walls are as close as possible to theyarn to be treated.

On the other hand, the above-mentioned chimney effect is uncontrollableand necessarily irregular. It gives rise to variable losses of heat andconsequently to harmful variations of the temperature in the heatingelements.

The present invention relates to an improvement in heating elements offalse-twist machines, for crimping synthetic textiles, notably in thecase of bent tubular heating elements according to French Patent1,140,992. The invention consists in producing a constant and controlledcirculation in all the elements of one machine, this circulation beingsufiicient to expel the heavy fumes resulting from the vaporization ofsizing oil from the heating elements.

The invention consists notably in aspirating the fumes in a constant andcontrolled manner as they leave the heating elements and in recycling atleast part of the aspirated air feed from fumes.

The invention will be better understood by referring to the followingdescription taken in connection with the accompanying drawing in which aspecific and preferred embodiment has been set forth for purposes ofillustration.

In the drawing:

FIGURE 1 is a diagrammatic view of an apparatus embodying the inventionand FIGURE 2 is a cross sectional view of a modification of FIGURE 1taken on the axis of the tube 1.

In a false-twist machine, the heating elements are heated, for example,by the passage of electric current through 3,283,414 Patented Nov. 8,1966 their mass or through an external resistance and so mount- As showned as to give exactly the same temperature. in FIGURE 1 a tube 1thermally insulated by an insulating casing 2 and fed by an electricsource 3 is connected at its baseto arelatively large chamber 4 for theadmission of compressed air. The said chamber 4 is formed with a smallinlet orifice 5 in its base.

If desired, asshown in FIGURE 2, a number of tubes 1 may extend througha common insulating casing, associated with a common admission chamber.

A fan 6 sucks in atmospheric air and the fumes leaving the tube 1through pipe 7 and delivers this air again to the tube 1 through a pipe10 connected to the chamber 4 by a duct 9. A calibrated valve 8 providedin the pipe 10 or in the chamber 4 allows a predetermined amount of theexcess air delivered by the fan to escape into a discharge chimney 10.The valve 8 is adjusted as a function of the desired speed of the airwithin the tube 1, this speed being in turn a function of the pressurein the chamber 4. If a number of tubes identical to 1 are connected tothe same chamber 4, it follows that the speed of the air is identical inall tubes and is adjustable by adjustment of the pressure in the chamber4.

In another form, the air may be sent into the chamber 4 by means of acompressor (not shown) independent of the fan.

The superatmospheric pressure in the chamber 4 is generally rather low,for example of the order of 10 mm. of mercury. The chamber 4 may bethermally insulated.

The fumes which condense, for example, in the pipes 7 and 10 may berecovered.

The valve 8 may be an electromagnetic valve which increases thecirculation in the event of a mechanical accident, for the purpose ofrapidly cooling the heating elements.

It is to be noted that the described improvement does not in any waygive rise to an appreciable increase in heat requirements, owing to therecycling of a part of the air extracted from the heating elements withthe fumes.

In operation, the filaments 11 extend vertically through the chamber 4,through the tubes 1 and through an opening at the junction of tubes 1land 7. The yarn is passed upwardly. Atmospheric air is drawn into thetube 7 and mixed with recirculated air from chamber 4 in the desiredproportions.

Preferably the pressure within the chamber 4 is maintained within arange differing only from about five to about fifty mm. of mercury aboveatmospheric; and more preferably from about five to about twenty-fivemm. of mercury. The optimum presure is regulated in accordance with thesize opening in flue 10, regulated by valve 8. The impure air isexhausted from the system via flue 10 rather than permittingcontamination of the factory space.

The ratio of atmospheric air pulled into the system and recirculated airis best regulated to provide the optimum temperature for processing theyarn 11. This will of course vary with atmospheric temperature and isreadily determined by simple well known mathematical calcula tions or bysimple manual adjustments of the flue opening and for speed to give thedesired temperature and pressure, and also the quantum of exhaust air.

Obviously, these same principles apply whether a series of tubes 1 areemployed or whether a plurality of the tubes 1 are connected inparallel.

What is claimed is:

1. Apparatus for recovering the vapors evolved in the high temperaturetreatment of textile filaments containing volatile oils comprising aheating tube through which said filaments pass having means for heatingsaid filaments to a temperature to vaporize at least a portion of theoil carried thereby, a pressure chamber disposed at the inlet end ofsaid tube and adapted to carry air under pressure to cause circulationthereof through said tube to the vdischarge end thereof, a condensermeans connected tothe discharge end of said heating tube, means causingcirculation of air from said pressure chamber through said heating tubeand through said condenser means for removing and condensing the vaporsfrorn'said heating tube, and

means recirculating 'a portion of the air from said condenser means tosaid pressure chamber. a

2. Apparatus as set forth in claim 1 in which a fan is disposed in saidcondenser means for causing said circu- 3 lation.

3. Apparatus'as set forth in claim 1 including a conltrol valve in saidcondenser means to control the relative quantity of air recirculated tosaid pressure chamber.

4. Apparatus as set forth in claim 1 including a plurality of heatingtubes associated with a common pressure chamber and connected for thecommon control of the circulation theret-hrough.

References Cited by the Examiner FREDERICK L. MA'ITES'ON, JR., PrimaryExaminer.

C. R. REMKE, Assistant Examiner.

1. APPARATUS FOR RECOVERING THE VAPORS EVOLVED IN THE HIGH TEMPERATURETREATMENT OF TEXTILE FILAMENTS CONTAINING VOLATILE OILS COMPRISING AHEATING TUBE THROUGH WHICH SAID FILAMENTS PASS HAVING MEANS FOR HEATINGSAID FILAMENTS TO A TEMPERATURE TO VAPORIZE AT LEAST A PORTION OF THEOIL CARRIED THEREBY, A PRESSURE CHAMBER DISPOSED AT THE INLET END OFSAID TUBE AND ADAPTED TO CARRY AIR UNDER PRESSURE TO CAUSE CIRCULATIONTHEREOF THROUGH SAID TUBE TO THE DISCHARGE END THEREOF, A CONDENSERMEANS CONNECTED TO THE DISCHARGE END OF SAID HEATING TUBE, MEANS CAUSINGCIRCULATION OF AIR FROM SAID PRESSURE CHAMBER THROUGH SAID HEATING TUBEAND THROUGH SAID CONDENSER MEANS FOR REMOVING AND CONDENSING THE VAPORSFROM SAID HEATING TUBE, AND MEANS RECIRCULATING A PORTION OF THE AIRFROM SAID CONDENSER MEANS TO SAID PRESSURE CHAMBER.